Hydraulic control device

Abstract

A first-type passage switching valve is in an oil supply line connecting a friction element to an N/H type pressure control valve and a second-type passage switching valve is in another oil supply line connecting another friction element to an N/L type pressure control valve. A working-pressure output valve outputs a hydraulic working pressure to each of the first-type and the second-type passage switching valves. The first-type passage switching valve changes communication condition from a first state connecting the friction element and the pressure control valve with each other to a second state connecting the friction element and a drain side with each other, or vice versa. The second-type passage switching valve changes communication condition from a first state connecting the friction element and the pressure control valve with each other to a third state connecting the friction element and a hydraulic pressure source with each other, or vice versa.

What is claimed is: 
     
       1. A hydraulic control device for an automatic transmission apparatus of a vehicle, which includes multiple friction elements; and a hydraulic-pressure producing unit configured to output a line pressure of a high pressure, which is higher than atmospheric pressure; the hydraulic control device being configured to adjust a hydraulic control pressure to be operatively supplied to each of the friction elements by use of the line pressure, wherein the hydraulic control pressure is adjusted at a value between the line pressure and a drain pressure which is equal to the atmospheric pressure, the hydraulic control device comprising:
 multiple hydraulic-pressure control units provided for each of the friction elements, each of the hydraulic-pressure control units being electrically controlled based on a command value for the hydraulic control pressure in order to adjust the hydraulic control pressure in accordance with an electric power supply amount and to output the hydraulic control pressure, and each of the hydraulic-pressure control units is a normally-high type control unit, so that the line pressure of the hydraulic-pressure producing unit is outputted from the hydraulic-pressure control unit when no electric power is supplied to the hydraulic-pressure control unit; 
 multiple oil supply lines provided for each of the friction elements, each of the oil supply lines connecting each of the hydraulic-pressure control units to the respective friction element in order to supply the hydraulic control pressure outputted from the hydraulic-pressure control units to the respective friction element; 
 a passage switching unit provided in at least one of the oil supply lines, a communication condition of the passage switching unit being configured to change from a first communication state to a second communication state, or vice versa, wherein the passage switching unit has a first oil chamber and a second oil chamber, and wherein the friction element is communicated to the hydraulic-pressure control unit via the second oil chamber in the first communication state and the friction element is communicated to a drain port of the passage switching unit via the second oil chamber in the second communication state; and 
 a hydraulic-pressure output unit configured to select one of the line pressure and the drain pressure depending on an electric power supply condition thereto and output a selected hydraulic pressure as a hydraulic working pressure to the first oil chamber of the passage switching unit, 
 wherein the passage switching unit has a first pressure receiving portion in the first oil chamber, the first pressure receiving portion being configured to receive the hydraulic working pressure outputted from the hydraulic-pressure output unit and the passage switching unit has a second pressure receiving portion in the second oil chamber, the second pressure receiving portion being configured to receive a clutch pressure of the friction element, which is a hydraulic pressure in the friction element, 
 wherein a pressure receiving direction of the hydraulic working pressure to be applied to the first pressure receiving portion of the first oil chamber and a pressure receiving direction of the clutch pressure to be applied to the second pressure receiving portion of the second oil chamber are opposed to each other in an axial direction of the passage switching unit, and 
 wherein a pressure receiving condition at the first and the second pressure receiving portions is changed by controlling the electric power supply condition to the hydraulic-pressure output unit and/or the hydraulic-pressure control unit connected to the passage switching unit in order to change the communication condition of the passage switching unit from the first communication state to the second communication state, or vice versa. 
 
     
     
       2. The hydraulic control device according to  claim 1 , wherein
 the first pressure receiving portion is mechanically coupled to the second pressure receiving portion, and 
 the communication condition of the passage switching unit is changed to the second communication state when an acting force by the hydraulic working pressure at the first pressure receiving portion is larger than an acting force by the clutch pressure at the second pressure receiving portion. 
 
     
     
       3. The hydraulic control device according to  claim 1 , wherein
 the first pressure receiving portion is mechanically coupled to the second pressure receiving portion. 
 
     
     
       4. The hydraulic control device according to  claim 1 , wherein
 the first pressure receiving portion is mechanically coupled to the second pressure receiving portion, and 
 the passage switching unit has a spring configured to bias the first and the second pressure receiving portions in a direction opposite to the pressure receiving direction at the first pressure receiving portion for the hydraulic working pressure. 
 
     
     
       5. The hydraulic control device according to  claim 1 , wherein
 the hydraulic-pressure output unit is configured to be electrically operated in a transient state, in which a coupling condition of friction plates of the friction element is changed from an engaged condition to a dis-engaged condition, or vice versa, and 
 no electric current is supplied to the hydraulic-pressure output unit in a steady state, in which the engaged condition or the dis-engaged condition of the friction plates is maintained. 
 
     
     
       6. The hydraulic control device according to  claim 5 , wherein
 the communication condition of the passage switching unit is in the first communication state when the friction element is in the transient state, and 
 an orifice is provided in a working-oil supply line, which connects the hydraulic-pressure output unit to the passage switching unit. 
 
     
     
       7. The hydraulic control device according to  claim 6 , wherein
 the working-oil supply line has a bypass passage bypassing the orifice, 
 a check valve is provided in the bypass passage, and 
 the check valve closes the bypass passage when no electric current is supplied to the hydraulic-pressure output unit, while the bypass passage is opened by the check valve when an electric power is supplied to the hydraulic-pressure output unit, so that the working oil is allowed to flow through the bypass passage. 
 
     
     
       8. The hydraulic control device according to  claim 1 , wherein
 the passage switching unit has a valve member of a spool type, and 
 the first and the second pressure receiving portions are formed in the valve member of the spool type. 
 
     
     
       9. The hydraulic control device according to  claim 1 , wherein
 the passage switching unit is provided in each of the oil supply lines, and 
 the hydraulic-pressure output unit is configured to output the selected hydraulic pressure to each of the passage switching units. 
 
     
     
       10. The hydraulic control device according to  claim 1 , wherein
 the hydraulic-pressure output unit has a coil and is configured to select one of the line pressure and the drain pressure when an electromagnetic force is generated upon receiving an electric power supply, so that the selected hydraulic pressure is outputted as the hydraulic working pressure. 
 
     
     
       11. The hydraulic control device according to  claim 1 , wherein
 each of the hydraulic-pressure control units has a coil configured to generate an electromagnetic force, a magnitude of which is controlled by the electric power supply amount to the coil, in order to adjust the hydraulic pressure at the value between the line pressure and the drain pressure and to output the adjusted hydraulic pressure as the hydraulic control pressure. 
 
     
     
       12. The hydraulic control device according to  claim 1 , wherein
 the electric power supply to the hydraulic-pressure control unit is cut off after the hydraulic working pressure outputted from the hydraulic-pressure output unit is changed to the line pressure when the communication condition of the passage switching unit is changed from the first communication state to the second communication state. 
 
     
     
       13. The hydraulic control device according to  claim 1 , wherein
 the hydraulic working pressure to be outputted from the hydraulic-pressure output unit is changed to the drain pressure after the electric power supply to the hydraulic-pressure control unit has been started when the communication condition of the passage switching unit is changed from the second communication state to the first communication state. 
 
     
     
       14. A hydraulic control device for an automatic transmission apparatus of a vehicle, which includes multiple friction elements; and
 a hydraulic-pressure producing unit configured to output a line pressure of a high pressure, which is higher than atmospheric pressure; 
 the hydraulic control device being configured to adjust a hydraulic control pressure to be operatively supplied to each of the friction elements by use of the line pressure, wherein the hydraulic control pressure is adjusted at a value between the line pressure and a drain pressure, which is equal to the atmospheric pressure, the hydraulic control device comprising: 
 multiple hydraulic-pressure control units provided for each of the friction elements, each of the hydraulic-pressure control units being electrically controlled based on a command value for the hydraulic control pressure in order to adjust the hydraulic control pressure in accordance with an electric power supply amount and to output the hydraulic control pressure, and each of the hydraulic-pressure control units is a normally-low type control unit, so that the drain pressure is outputted from the hydraulic-pressure control unit when no electric power is supplied to the hydraulic-pressure control unit; 
 multiple oil supply lines provided for each of the friction elements, each of the oil supply lines connecting each of the hydraulic-pressure control units to the respective friction element in order to supply the hydraulic control pressure outputted from the hydraulic-pressure control unit to the respective friction element; 
 a passage switching unit provided in at least one of the oil supply lines, a communication condition of the passage switching unit being configured to change from a first communication state to a third communication state, or vice versa, wherein the passage switching unit has a first oil chamber, a second oil chamber and a third oil chamber, wherein the friction element is communicated to the hydraulic-pressure control unit via the third oil chamber in the first communication state and the friction element is communicated to the hydraulic-pressure producing unit via the third oil chamber in the third communication state; and 
 a hydraulic-pressure output unit configured to select one of the line pressure and the drain pressure depending on an electric power supply condition thereto and output a selected hydraulic pressure as a hydraulic working pressure to the first oil chamber of the passage switching unit, 
 wherein the passage switching unit has a first pressure receiving portion in the first oil chamber, the first pressure receiving portion being configured to receive the hydraulic working pressure outputted from the hydraulic-pressure output unit, the passage switching unit has a second pressure receiving portion in the second oil chamber, the second pressure receiving portion being configured to receive a clutch pressure of the friction element, which is a hydraulic pressure in the friction element, and the passage switching unit further has a third pressure receiving portion in the third oil chamber, the third pressure receiving portion being configured to receive the line pressure from the hydraulic-pressure producing unit, 
 wherein a direction of the hydraulic working pressure to be applied to the first pressure receiving portion of the first oil chamber and a direction of the clutch pressure to be applied to the second pressure receiving portion are opposed to a direction of the line pressure to be applied to the third pressure receiving portion of the third oil chamber, and 
 wherein a pressure receiving condition at the first and the second pressure receiving portions is changed by controlling the electric power supply condition to the hydraulic-pressure output unit and/or the hydraulic-pressure control unit connected to the passage switching unit in order to change the communication condition of the passage switching unit from the first communication state to the third communication state, or vice versa. 
 
     
     
       15. The hydraulic control device according to  claim 14 , wherein
 the first pressure receiving portion, the second pressure receiving portion and the third pressure receiving portion are mechanically coupled to one another, and 
 the communication condition of the passage switching unit is changed to the third communication state when a sum of an acting force by the hydraulic working pressure at the first pressure receiving portion and an acting force by the clutch pressure at the second pressure receiving portion is equal to or larger than an acting force by the line pressure at the third pressure receiving portion. 
 
     
     
       16. The hydraulic control device according to  claim 14 , wherein
 the first pressure receiving portion, the second pressure receiving portion and the third pressure receiving portion are mechanically coupled to one another, and 
 a pressure receiving area at the first pressure receiving portion is smaller than a pressure receiving area at the third pressure receiving portion. 
 
     
     
       17. The hydraulic control device according to  claim 16 , wherein
 the passage switching unit has a spring configured to bias the first, the second and the third pressure receiving portions in a direction opposite to the pressure receiving direction at the third pressure receiving portion for the line pressure. 
 
     
     
       18. The hydraulic control device according to  claim 14 , wherein
 the hydraulic-pressure output unit is configured to be electrically operated in a transient state, in which a coupling condition of friction plates of the friction element is changed from an engaged condition to a dis-engaged condition, or vice versa, and 
 no electric current is supplied to the hydraulic-pressure output unit in a steady state, in which the engaged condition or the dis-engaged condition of the friction plates is maintained. 
 
     
     
       19. The hydraulic control device according to  claim 18 , wherein
 the communication condition of the passage switching unit is in the first communication state when the friction element is in the transient state, and 
 an orifice is provided in a working-oil supply line, which connects the hydraulic-pressure output unit to the passage switching unit. 
 
     
     
       20. The hydraulic control device according to  claim 19 , wherein
 the working-oil supply line has a bypass passage bypassing the orifice, 
 a check valve is provided in the bypass passage, and 
 the check valve closes the bypass passage when no electric current is supplied to the hydraulic-pressure output unit, while the bypass passage is opened by the check valve when an electric power is supplied to the hydraulic-pressure output unit, so that the working oil is allowed to flow through the bypass passage. 
 
     
     
       21. The hydraulic control device according to  claim 14 , wherein
 the passage switching unit has a valve member of a spool type, and 
 each of the first, the second and the third pressure receiving portions is formed in the valve member of the spool type. 
 
     
     
       22. The hydraulic control device according to  claim 14 , wherein
 the passage switching unit is provided in each of the oil supply lines, and 
 the hydraulic-pressure output unit is configured to output the selected hydraulic pressure to each of the passage switching units. 
 
     
     
       23. The hydraulic control device according to  claim 14 , wherein
 the hydraulic-pressure output unit has a coil and is configured to select one of the line pressure and the drain pressure when an electromagnetic force is generated upon receiving an electric power supply, so that the selected hydraulic pressure is outputted as the hydraulic working pressure. 
 
     
     
       24. The hydraulic control device according to  claim 14 , wherein
 each of the hydraulic-pressure control units has a coil configured to generate an electromagnetic force, a magnitude of which is controlled by the electric power supply amount to the coil, in order to adjust the hydraulic pressure at the value between the line pressure and the drain pressure and to output the adjusted hydraulic pressure as the hydraulic control pressure. 
 
     
     
       25. The hydraulic control device according to  claim 14 , wherein
 the electric power supply to the hydraulic-pressure control unit is cut off after the hydraulic working pressure outputted from the hydraulic-pressure output unit is changed to the line pressure when the communication condition of the passage switching unit is changed from the first communication state to the third communication state. 
 
     
     
       26. The hydraulic control device according to  claim 14 , wherein
 the hydraulic working pressure to be outputted from the hydraulic-pressure output unit is changed to the drain pressure after the electric power supply to the hydraulic-pressure control unit has been started when the communication condition of the passage switching unit is changed from the third communication state to the first communication state.